"Johnny, you go deep down the right side. Pete, you run a 10 yard in from the left. Dave, you drift to the flat to my right." is not what the Patriots are running. The Patriots run a complicated offense, where the receiver has to read not just where he would go, but exactly where Brady would expect him to go, taking in all the context of every other route and the positioning of all the players on the field. Veterans, particularly veterans who've learned multiple systems, will usually pick that up more easily than a rookie, because the game has already slowed down for them, and they're just adapting to changes rather than having to learn from scratch the way a rookie does. Even so, we've seen plenty of examples of even veterans who don't, or won't, learn how to play in the system (i.e. Galloway, Chad Johnson). It's just not an easy system to learn.
So, when I talk about not expecting much from Harry, it's not about me taking a slap at Harry. It's an acknowledgment that the system is a complicated one, and that even good rookies have a learning curve.